Enhanced photodynamic antitumor effect on gastric cancer by a novel photosensitive stealth liposome.

Lipophilic photosensitizers hold potential for cancer photodynamic therapy. We sought to develop a novel photosensitive stealth liposome (PSSL) which incorporating a lipophilic photosensitizer into its lipid bilayer and to examine its photoactivity. We prepared PSSL composed of lipophilic chlorin e6 (Ce6) ester, dilauroylphosphatidylcholine, dioleoylphosphatidylethanolamine and distearoyl-phosphoethanolamine-N-[poly (ethylene glycol) 2000] and evaluated its photodynamic effect against gastric cancer cell lines and tumor-bearing nude mice models. In gastric cancer cell lines, LC(80) of PSSL was a maximum of 53 times as low as that of Ce6 sodium salt (Ce6-Na). PSSL completely destroyed all tumors in animal models and tumor recurrence levels were minimal (1.5 +/- 0.9%). PSSL achieved greater photodynamic effects in gastric cancer cell lines and in murine models than Ce6-Na. PSSL holds promise for photodynamic therapy for gastric cancer.